TheDukeofFromeJohnLangtonwithhiswife,theirbabybornaftercomplicationsduringchildbirth,adomineeringnanny,nurserymaidandvaletarriveatMontagueHallforLadyFelicia'sYuletideball.Duringtheeveningthebabyistakenfromhiscot.InspectorMallorysuspectsaninsidejobbythevaletwhenhissecretwifearriveswhileBrownismoreinterestedinthebirthofthebabyatahomeforunmarriedmothers.MrsMcCarthyunderpressurefromthediocesetoprovideaChristmasservicefitforaDukereceivesunexpectedhelpfromavagrantshefindsintheconfessional.
